In a motor vehicle, it is known to use sensors for measuring a parameter such as, for example, the rotational speed or the position of a drive shaft.
Such a sensor includes, in a known manner, a body made from a thermoplastic material overmolded around an electronic measurement module. This body makes it possible both to mount the sensor in a motor vehicle and to protect the electronic module from the gases and the projections generated by the motor vehicle.
To produce this overmolding, it is known to mount the electronic measurement module on a positioning carrier in a mold, and then to position the carrier in said mold and to overmold the body around the carrier and the electronic measurement module by injecting thermoplastic material.
Such overmolding is specific to each type of sensor with regard both to the volume of thermoplastic material that is injected and to the shape of the mold. It is thus necessary, for each type of sensor, to create a suitable mold and to carry out injection volume checking tests, which may prove complex, time-consuming and expensive, and therefore exhibits significant drawbacks.
When overmolding, it is also known to form sealing fins that take the form of ribs extending around sensing zones through which projections or gases generated by the motor vehicle could penetrate.
These sensing zones may for example correspond to the interfaces between the electronic measurement module or the positioning carrier and the body of the sensor.
The fins are thus often placed between zones where the differences in injected volumes of thermoplastic material may be very large. In this case, after the injection of thermoplastic material and when the latter cools, the thermoplastic material situated in the high-volume zones shrinks to a greater extent and draws the thermoplastic material situated in the low-volume zones, thereby possibly generating microcracks in the fins and a lack of sealtightness of the sensor, and therefore exhibits a major drawback.
One known solution for at least partly solving this problem consists in using a tool or a machine to maintain a pressure on the thermoplastic material in the low-volume zones when the thermoplastic material cools in order to avoid an excessively significant shrinkage toward the high-volume zones.
However, such a method is complex, time-consuming and expensive, thereby again exhibiting significant drawbacks.